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The absence of a natural animal model is one of the main challenges in Alzheimer's disease research. Despite the challenges of using nonhuman primates in studies, these animals can bridge mouse models and humans, as nonhuman primates are phylogenetically closer to humans and can spontaneously develop AD-type pathology. The capuchin monkey, a New World primate, has recently attracted attention due to its skill in creating and using instruments. We analyzed one capuchin brain using structural 7 T MRI and performed a neuropathological evaluation of three animals. Alzheimer-type pathology was found in the two of the capuchins. Widespread ß-amyloid pathology was observed, mainly in focal deposits with variable morphology and a high density of mature plaques. Notably, plaque-associated dystrophic neurites associated with disruption of axonal transport and early cytoskeletal alteration were frequently found. Unlike in other species of New World monkeys, cerebral arterial angiopathy was not the predominant form of ß-amyloid pathology. Additionally, abnormal aggregates of hyperphosphorylated tau, resembling neurofibrillary pathology, were observed in the temporal and frontal cortex. Astrocyte hypertrophy surrounding plaques was found, suggesting a neuroinflammatory response. These findings indicate that aged capuchin monkeys can spontaneously develop Alzheimer-type pathology, indicating that they may be an advantageous animal model for research in Alzheimer's disease.

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BACKGROUND: Frontotemporal dementia (FTD) is a frequent cause of young-onset dementia and represents a major challenge for the diagnosis and clinical management. It is essential to evaluate the difficulties faced by physicians on the diagnostic workup and on patient care. OBJECTIVE: The aim of this study was to investigate the current practices and the local limits on the diagnosis and management of FTD in Brazil. METHODS: We elaborated an online survey, composed of 29 questions and divided in four parts, comprising questions about existing health facilities, clinical practices related to FTD, and suggestions to increment the national research on FTD. The invitation to participate was sent by email to all neurologists affiliated to the Brazilian Academy of Neurology (n = 3658), and to all physicians who attended the XII Meeting of Researchers on Alzheimer's disease, in 2019 (n = 187). The invitation was also diffused through social media. RESULTS: 256 Brazilian physicians answered the questionnaire. The three most relevant disorders for the differential diagnosis of FTD were Alzheimer's disease (AD) (n = 211), bipolar disorder (n = 117) and dementia with Lewy bodies (n = 92). Most respondents (125/256) reported the difficulty in performing genetic testing as the main limit in the diagnostic of FTD. 93% and 63% of participants considered that the assessment of social cognition and AD CSF biomarkers are useful for the diagnosis of FTD, respectively. CONCLUSIONS: The present study may provide valuable insights for the medical education and clinical training of physicians, and to foster future research on FTD in Brazil.

ANTECEDENTES: A demência frontotemporal (DFT) é causa frequente de demência pré-senil e representa um desafio em termos de diagnóstico e de manejo clínico. É essencial avaliar as dificuldades existentes na propedêutica e nos cuidados médicos. OBJETIVO: Investigar as práticas médicas e as dificuldades para diagnóstico e manejo da DFT no Brasil. MéTODOS: Elaborou-se um questionário online, composto de 29 questões, divididas em quatro partes, com perguntas sobre infraestrutura existente, práticas clínicas relacionadas à DFT e sugestões para desenvolver a pesquisa nacional na área. O convite para participação foi enviado por e-mail a todos neurologistas afiliados à Academia Brasileira de Neurologia (n = 3658), e aos médicos que participaram da XII Reunião de Pesquisadores de Doença de Alzheimer, em 2019 (n = 187). O convite também foi divulgado através de mídias sociais. RESULTADOS: 256 médicos brasileiros responderam o questionário. Os três principais diagnósticos diferenciais de DFT foram doença de Alzheimer (n = 211), transtorno bipolar (n = 117) e demência com corpos de Lewy (n = 92). A maior parte dos respondedores (125/256) apontou a dificuldade em realizar testagem genética como o maior limite no diagnóstico de DFT. 93% e 63% dos respondedores indicaram que a avaliação de cognição social e o uso de biomarcadores liquóricos de doença de Alzheimer são úteis no diagnóstico de DFT, respectivamente. CONCLUSõES: Estes resultados devem ser considerados na educação e treinamento médicos, e no desenvolvimento da pesquisa brasileira em DFT.

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Abstract Background Frontotemporal dementia (FTD) is a frequent cause of young-onset dementia and represents a major challenge for the diagnosis and clinical management. It is essential to evaluate the difficulties faced by physicians on the diagnostic workup and on patient care. Objective The aim of this study was to investigate the current practices and the local limits on the diagnosis and management of FTD in Brazil. Methods We elaborated an online survey, composed of 29 questions and divided in four parts, comprising questions about existing health facilities, clinical practices related to FTD, and suggestions to increment the national research on FTD. The invitation to participate was sent by email to all neurologists affiliated to the Brazilian Academy of Neurology (n = 3658), and to all physicians who attended the XII Meeting of Researchers on Alzheimer's disease, in 2019 (n = 187). The invitation was also diffused through social media. Results 256 Brazilian physicians answered the questionnaire. The three most relevant disorders for the differential diagnosis of FTD were Alzheimer's disease (AD) (n = 211), bipolar disorder (n = 117) and dementia with Lewy bodies (n = 92). Most respondents (125/256) reported the difficulty in performing genetic testing as the main limit in the diagnostic of FTD. 93% and 63% of participants considered that the assessment of social cognition and AD CSF biomarkers are useful for the diagnosis of FTD, respectively. Conclusions The present study may provide valuable insights for the medical education and clinical training of physicians, and to foster future research on FTD in Brazil.

Resumo Antecedentes A demência frontotemporal (DFT) é causa frequente de demência pré-senil e representa um desafio em termos de diagnóstico e de manejo clínico. É essencial avaliar as dificuldades existentes na propedêutica e nos cuidados médicos. Objetivo Investigar as práticas médicas e as dificuldades para diagnóstico e manejo da DFT no Brasil. Métodos Elaborou-se um questionário online, composto de 29 questões, divididas em quatro partes, com perguntas sobre infraestrutura existente, práticas clínicas relacionadas à DFT e sugestões para desenvolver a pesquisa nacional na área. O convite para participação foi enviado por e-mail a todos neurologistas afiliados à Academia Brasileira de Neurologia (n = 3658), e aos médicos que participaram da XII Reunião de Pesquisadores de Doença de Alzheimer, em 2019 (n = 187). O convite também foi divulgado através de mídias sociais. Resultados 256 médicos brasileiros responderam o questionário. Os três principais diagnósticos diferenciais de DFT foram doença de Alzheimer (n = 211), transtorno bipolar (n = 117) e demência com corpos de Lewy (n = 92). A maior parte dos respondedores (125/256) apontou a dificuldade em realizar testagem genética como o maior limite no diagnóstico de DFT. 93% e 63% dos respondedores indicaram que a avaliação de cognição social e o uso de biomarcadores liquóricos de doença de Alzheimer são úteis no diagnóstico de DFT, respectivamente. Conclusões Estes resultados devem ser considerados na educação e treinamento médicos, e no desenvolvimento da pesquisa brasileira em DFT.

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"Frontotemporal dementia" (FTD) is a clinical syndrome characterized by the focal involvement of the frontal and/or temporal lobes. FTD has three clinical phenotypes: the behavioral variant and two linguistic subtypes, namely, non-fluent/agrammatic primary progressive aphasia (PPA-NF/A) and semantic PPA (PPA-S). FTD is the second most common cause of dementia in individuals under the age of 65 years. This article presents recommendations for the diagnosis of FTD in the Brazilian scenario, considering the three levels of complexity of the health system: primary health care, secondary and tertiary levels. Diagnostic guidelines are proposed, including cognitive testing, behavioral and language assessments, laboratory tests, and neuroimaging.

A "demência frontotemporal" (DFT) é uma síndrome clínica, cujo denominador comum é o acometimento focal dos lobos frontais e/ou temporais. A DFT tem três fenótipos clínicos distintos: a variante comportamental e dois subtipos linguísticos, a saber, a afasia progressiva primária não-fluente/agramática (APP-NF/A) e a afasia progressiva primária semântica (APP-S). A DFT é a segunda causa mais comum de demência em indivíduos com idade inferior a 65 anos, após a doença de Alzheimer. O presente artigo apresenta recomendações para diagnóstico da DFT no cenário brasileiro, considerando os três níveis de complexidade do sistema de saúde: atenção primária à saúde e níveis secundários. São propostos protocolos de investigação diagnóstica abrangendo testagem cognitiva, avaliação comportamental, avaliação fonoaudiológica, exames laboratoriais e de neuroimagem.

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RESUMO A "demência frontotemporal" (DFT) é uma síndrome clínica, cujo denominador comum é o acometimento focal dos lobos frontais e/ou temporais. A DFT tem três fenótipos clínicos distintos: a variante comportamental e dois subtipos linguísticos, a saber, a afasia progressiva primária não-fluente/agramática (APP-NF/A) e a afasia progressiva primária semântica (APP-S). A DFT é a segunda causa mais comum de demência em indivíduos com idade inferior a 65 anos, após a doença de Alzheimer. O presente artigo apresenta recomendações para diagnóstico da DFT no cenário brasileiro, considerando os três níveis de complexidade do sistema de saúde: atenção primária à saúde e níveis secundários. São propostos protocolos de investigação diagnóstica abrangendo testagem cognitiva, avaliação comportamental, avaliação fonoaudiológica, exames laboratoriais e de neuroimagem.

ABSTRACT "Frontotemporal dementia" (FTD) is a clinical syndrome characterized by the focal involvement of the frontal and/or temporal lobes. FTD has three clinical phenotypes: the behavioral variant and two linguistic subtypes, namely, non-fluent/agrammatic primary progressive aphasia (PPA-NF/A) and semantic PPA (PPA-S). FTD is the second most common cause of dementia in individuals under the age of 65 years. This article presents recommendations for the diagnosis of FTD in the Brazilian scenario, considering the three levels of complexity of the health system: primary health care, secondary and tertiary levels. Diagnostic guidelines are proposed, including cognitive testing, behavioral and language assessments, laboratory tests, and neuroimaging.

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BACKGROUND: In fewer than 1% of patients, AD is caused by autosomal dominant mutations in either the presenilin 1 (PSEN1), presenilin 2 (PSEN2), or amyloid precursor protein (APP) genes. The full extent of familial AD and frequency of these variants remains understudied in Latin American (LatAm) countries. Due to the rare nature of these variants, determining the pathogenicity of a novel variant in these genes can be challenging. Here, we use a systematic approach to assign the likelihood of pathogenicity in variants from densely affected families in Latin American populations. METHODS: Clinical data was collected from LatAm families at risk for DIAD. Symptomatic family members were identified and assessed by local clinicians and referred for genetic counseling and testing. To determine the likelihood of pathogenicity among variants of unknown significance from LatAm populations, we report pedigree information, frequency in control populations, in silico predictions, and cell-based models of amyloid-beta ratios. RESULTS: We identified five novel variants in the presenilin1 (PSEN1) gene from Brazilian and Mexican families. The mean age at onset in newly identified families was 43.5 years (range 36-54). PSEN1 p.Val103_Ser104delinsGly, p.Lys395Ile, p.Pro264Se, p.Ala275Thr, and p.Ile414Thr variants have not been reported in PubMed, ClinVar, and have not been reported in dominantly inherited AD (DIAD) families. We found that PSEN1 p.Val103_Ser104delinsGly, p.Lys395Ile, p.Pro264Se, and p.Ala275Thr produce Aß profiles consistent with known AD pathogenic mutations. PSEN1 p.Ile414Thr did not alter Aß in a manner consistent with a known pathogenic mutation. CONCLUSIONS: Our study provides further insights into the genetics of AD in LatAm. Based on our findings, including clinical presentation, imaging, genetic, segregations studies, and cell-based analysis, we propose that PSEN1 p.Val103_Ser104delinsGly, p.Lys395Ile, p.Pro264Se, and p.Ala275Thr are likely pathogenic variants resulting in DIAD, whereas PSEN1 p.Ile414Thr is likely a risk factor. This report is a step forward to improving the inclusion/engagement of LatAm families in research. Family discovery is of great relevance for the region, as new initiatives are underway to extend clinical trials and observational studies to families living with DIAD.

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BACKGROUND: The field of neurodegenerative dementia genetics has advanced significantly over the past two decades, but there are still more to be discovered (such as the gene mutation in some familial forms of dementia). OBJECTIVE: to provide a brief review of the most recent discoveries regarding monogenic dementia, and covering the most frequent genetic diseases that can cause dementia (neurodegenerative or not). METHODS: a review of the literature will be carried out. RESULTS: neurodegenerative dementias, vascular dementias and leukoencephalopathies caused by single pathogenic variants are presented. CONCLUSION: The spectrum of clinical presentations for most of the genes discussed is wide, and hence genetic testing in clinic should try to cover as many genes as possible.

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Abstract Background: The field of neurodegenerative dementia genetics has advanced significantly over the past two decades, but there are still more to be discovered (such as the gene mutation in some familial forms of dementia). Objective: to provide a brief review of the most recent discoveries regarding monogenic dementia, and covering the most frequent genetic diseases that can cause dementia (neurodegenerative or not). Methods: a review of the literature will be carried out. Results: neurodegenerative dementias, vascular dementias and leukoencephalopathies caused by single pathogenic variants are presented. Conclusion: The spectrum of clinical presentations for most of the genes discussed is wide, and hence genetic testing in clinic should try to cover as many genes as possible.

RESUMO Antecedentes: O campo da genética das demências neurodegenerativas avançou significativamente nas últimas duas décadas, mas ainda há mais a ser descoberto (como a mutação genética em algumas formas familiares de demência). Objetivo: fornecer uma breve revisão das descobertas mais recentes sobre demência monogênica, e abrangendo as doenças genéticas mais frequentes que podem causar demência (neurodegenerativa ou não). Métodos: será realizada uma revisão da literatura. Resultados: são apresentadas demências neurodegenerativas, demências vasculares e leucoencefalopatias causadas por variantes patogênicas únicas. Conclusão: O espectro de apresentações clínicas para a maioria dos genes discutidos é amplo e, portanto, os testes genéticos na clínica devem tentar cobrir o maior número possível de genes.

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